BOSTON -- The Red Sox filled a big need with 18 days to spare before the July 31 Trade Deadline, acquiring righty starter Andrew Cashner from the Orioles in exchange for Minor League infielder Noelberth Romero and Minor League outfielder Elio Prado on Saturday.

Cashner will report to the Red Sox on Sunday and make his first start on Tuesday against the Blue Jays at Fenway Park, president of baseball operations Dave Dombrowski said.

The fifth spot in the rotation has been a weakness for the Red Sox since Nathan Eovaldi went down in mid-April with a right elbow injury.

With the recent news that Eovaldi will pitch out of the bullpen in his return, Dombrowski focused on getting a starter to back his front four of Chris Sale, David Price, Eduardo Rodriguez and Rick Porcello.

There have been 16 occasions this season when the Sox have used a starter beyond those four pitchers or Eovaldi. Those starters have combined to go 2-7 with a 6.79 ERA while logging just 51 innings.

“Definitely gives us the improvement in that fifth spot, which we’ve scuffled for such a long time this year,” Dombrowski said. “He’s a guy that’s taken the ball and given six, seven innings on a consistent basis, so we like a lot of the things about him. We think he makes us better.”

The 32-year-old Cashner had a strong first half, going 9-3 with a 3.83 ERA in 17 starts. He completed at least seven innings in each of his past two starts and at least six innings in each of his last five, posting a 1.41 ERA since the start of June. On the season, Cashner has held left-handed hitters to a .182 batting average, a .499 OPS and only one home run.

“As far as what we like, he’s been throwing the ball well,” Dombrowski said. “Been in the big leagues for a long time. He’s throwing the ball as well as he probably ever has at this point, maybe not velocity-wise, because he was a very hard thrower earlier in his career.”

Cashner is in the final season of the two-year, $16 million contract he signed with the Orioles and will likely be a free agent at the end of the season. The contract did include a $10 million option for 2020 that automatically vests if he combines to pitch 340 innings in 2018-19. Cashner would need to pitch 90 1/3 more innings for the rest of this season for that to happen.

Cashner will earn roughly $3 million for the balance of this season. Due to the cash considerations the Red Sox acquired in the trade, the Orioles will pay $1.78 million of that, according to MLB Network contributor Joel Sherman.

With the trade, Cashner goes from a team that started the night 28-63 to one that is 50-41 and one game out in the American League Wild Card standings and 8 1/2 back in the AL East. The Red Sox won the World Series last season, and have nearly all of that roster back this season.

“He’s excited to be here, excited to pitch, excited to join the club, be part of a pennant race,” Dombrowski said.

Though reports had surfaced earlier in the season that Cashner would contemplate retirement if traded from Baltimore, Dombrowski said the veteran is fully on board with the move to the Red Sox.

“I talked to [the Orioles] in the process over the last couple of days about that, and [it was] something that got carried away in conversations so he’s not like that,” Dombrowski said.

Now that the Red Sox have their starter, it’s fair to wonder if Dombrowski will put his focus on the bullpen -- which has been a glaring weak spot of late -- in the days prior to the Deadline.

Dombrowski said that acquiring a reliever isn’t a certainty, and thinks his bullpen could improve with Eovaldi’s pending return, not to mention the recent return from suspension by knuckleballer Steven Wright.

“We are going to add Nathan Eovaldi. For some reason, people seem to not grasp on to that,” Dombrowski said. “He’s a big addition for us coming, and we feel he’ll be ready to go within about a week to join us on a full-time basis out there. So he is an addition to our bullpen. We just added Steven Wright recently so I don’t know if we’ll do anything else in that regard. We kind of like some of our guys out there.”

Romero, 17, made his professional debut this season with the Rookie-level Dominican Summer League Red Sox2. The right-handed hitter has appeared in 29 games, making 22 starts at third base, five at second base and two at shortstop. He has batted .264 (29-for-110) with two home runs, drawing 11 walks against 20 strikeouts.

Prado, 17, also made his professional debut this season with the DSL Red Sox2, batting .303 (37-for-122) with three home runs in 33 games. He has made 18 starts in center field, seven in right field and six in left field. The right-handed hitter has scored 26 runs with 26 RBIs, adding nine stolen bases with 20 walks and 21 strikeouts.

“I commend [assistant general manager] Eddie [Romero] and his staff for finding [the] players they have in Latin America, players that are a long way away from our perspective, but players that they like and did a good job in signing them,” Dombrowski said. “Also we worked out some financial matters because there’s cash involved coming and we thank [assistant GM] Brian [O’Halloran] for his work on that. So everything fit together for us and we kept looking at the different names that may make sense.”

For the Red Sox, who are trying to rebuild a farm system that has been compromised by blockbuster trades in recent years, it was important to fill a need without dealing any of their top prospects.

“And we really, we’re trying to win. We have a chance to win. We know we have to play better,” Dombrowski said. “We’re trying to rebuild our system, and I think we’re getting to the point where we’re starting to get there. So we’re trying to win, but in addition, build back.”